Not meaning to drive you crazier than this is already, but how about I
through a few crazy ideas your way. I'm assuming you're wanting to use
both airbrushes at some point during projects or else you would have
just bought an Iwata hose. So...
You could use a quick disconnect setup, a female for on the compressor
side, a male on the AB (hose) side, an Iwata hose with a male quick
disconnect adapter and then switch between the two when needed.
Or...
Setup a 2 hose manifold, Iwata and Paasche. That would come in real
handy during projects, having 2 AB's hooked up and ready to go.
Or...
Find out why the heck the adapter doesn't fit your Paasche hose.
Just a few thoughts.